The invention relates to a method for making a microcircuit card comprising a support card and a module carrying the microcircuit, the module being installed in an open cavity in said support card. A more particular object of the invention is to combat a type of fraud consisting of demounting a module of this kind without affecting its functions, in order to transplant it into another support card.
The development of microcircuit cards in all fields is constantly calling into question security criteria. One of these criteria is the fact that any attempt to extract the module from the support card must lead to failure, i.e. to destruction of the microcircuit and/or its connections. The need to make progress in this field is keenly felt, especially since producing microcircuit identity cards has been envisaged.
The module that is installed in the cavity in the support card comprises a support film forming a printed circuit and carrying the microcircuit on one side. In most of the technologies currently used it is possible to demount the module without destroying it. This is because the module is often stuck to a peripheral flat defined between the open side and the bottom of the cavity, the microcircuit, which is often coated, being housed in the cavity itself. It is relative easy to insert a tool between the edge of the cavity and that of the module, to detach the latter. If this is done carefully, separation does not lead to the destruction of the microcircuit and/or its connections. Adding a drop of adhesive to connect the bottom of the cavity to the coating of the microcircuit has been proposed. However, demounting remains possible if a tool can be inserted between the resin of the coating and the adhesive. Another technique, proposed by the applicant, consists in depositing the resin protecting the microcircuit into the cavity itself and coating the microcircuit with this resin before the resin is polymerized. This technique makes the module more difficult to demount but the results are difficult to control since they depend greatly on the adherence of the resin to the walls of the cavity and in particular to its bottom. The invention aims to improve this technique.